In recent years, demands for storage devices, such as magnetic disk devices, magneto-optical disk devices, and optical disk devices, are expanding. A storage device has incorporated therein a disk-shaped storage medium for reading and writing information via a head. With the expansion of demand for storage devices, information recording density of a storage medium has been significantly improved.
In such a high-density storage medium, to accurately position a head at a target track, auto control called servo control is used. In the storage medium, signal patterns called servo information (servo data) for use in servo control are written.
The servo information is written in the storage medium with a Servo Track Writer (STW) mode using a device called an STW (for example, a self STW mode, a stack-media STW mode, or a copy STW mode, which will be explained further below) or a magnetic printing mode. That is, from a plurality of modes of writing servo information, a manufacturer of the storage medium can arbitrarily use any one of the modes to write servo information in the storage medium.
However, each of these servo-information write modes has advantages and disadvantages in a storage-device manufacturing process. For example, the stack-media STW mode does not require much time to prepare for steps prior to a servo-information write process, allowing servo information to be written in approximately ten storage media at once, but do require much time to write servo information itself.
On the other hand, magnetic printing does not require much time to write servo information, allowing servo information to be written in a large number of storage media at once, but do require much time and cost to generate a model of servo patterns of servo information, which is called a master stamper.
Meanwhile, a manufacturer manufacturing storage devices is required to arrange a plan to produce storage devices in consideration of the number of orders for storage devices from customers and manufacturing yield of storage devices, and is also required to manage parts inventory. An increase in inventory due to excessive manufacturing of storage media is undesirable in view of manufacturing cost. Therefore, the entire manufacturing process from receiving an order for storage devices from a customer through generating servo patterns and then inspecting products before shipping to shipping them to the customer is desirably completed within the shortest possible period of time.
To do this, in consideration of the number of orders for storage devices from customers and manufacturing yield of storage devices, some or all of the servo-information write modes are combined as appropriate to write the servo information in the storage media. With this, production planning for optimizing the period of the entire manufacturing process can be achieved. That is, in one storage-device manufacturing process, storage devices with storage media having servo information written therein with different modes are produced in a mixed manner.
In general, when servo information is written with different modes, a shipping inspector has to recognize in advance which servo-information write mode was used to write the servo information in each storage medium and then perform an inspection process at the time of shipping according to the relevant mode.
However, when storage devices with servo information written therein with different modes are produced in a mixed manner in one storage-device manufacturing process due to the reasons, the servo-information write mode has to be correctly identified for each storage device so as to perform an inspection process at the time of shipping.
As a conventional technology of identifying a servo-information write mode, a storage device has been suggested in which a head that reads information stored in a storage medium selects from a plurality of types of servo information written in one storage medium is the one having the highest affinity for the characteristics of the head and capable of accurately reading information. Also, another storage device has been suggested in which a storage medium is provided with a protective area where information for identifying a device that has recorded servo information in the storage medium is stored. For example, these conventional technologies are disclosed in Japanese Laid-open Patent Publication Nos. 2006-147104 and 2006-221771.
However, in the conventional technologies mentioned above, in an inspection process at the time of shipping performed on a storage device with a storage medium incorporate therein, the inspector has to recognize in advance which servo-information write mode was used to write servo information and conduct an inspection by using an inspection program for each servo-information write mode.
Therefore, in the conventional technologies, in an inspection process, mixed presence of storage devices with different servo-information write modes is not allowed. That is, for each storage device with a different servo-information write mode, the inspection program has to be switched to a corresponding one, and such switching involves a temporary halt of the manufacturing line, thereby decreasing production efficiency.
Moreover, storage devices having storage media with servo information recorded therein with different servo-information write modes are operation-controlled by different control programs and are tested by different test programs. Therefore, different control programs have to be generated for the respective servo-information write modes, thereby inviting an increase in the number of processes for manufacturing storage devices and inhibiting a reduction in manufacturing cost and time of storage devices.